Training, information, and encouragement for new amateur radio operators.

Ground

Ever wonder why RF grounds should be flat straps and not regular wires?

This is because ordinary wires are not good conductors at frequencies higher than 50-60Hz. This complicates wiring and bonding requirements.

Impedance (effectively, AC resistance) of a conductor increases with frequency and length due to inductive reactance. The higher the frequency, the greater the impedance.

All conductors have some measurable inductance, and it doesn’t take much to yield significant impedance. At KHz or MHz frequencies, long round wires might present hundreds or even thousands of Ohms impedance; not suitable for grounding.

A good ground has less than one ohm impedance. This is a genuine safety issue.

Since inductive reactance increases with frequency and length, safety grounds and module bonds need to be something other than long round wires when radio frequencies are involved.

When high frequency grounding is required, use short, wide, and flat conductive straps. The high aspect ratio minimizes electrical inductance vs. a round wire, as does a short conductor. This lowers the ground wire’s impedance at higher frequencies.

So now you know. Keep it flat and short (KIFS is a lousy acronym).

It’s not just a suggestion; this one might just bite you if you don’t heed the guideline!